1. Technical Field
The present invention relates to a semiconductor device, and to a technique applicable to, for example, a semiconductor device having a diode.
2. Related Art
Rectifying devices are often used in an electric circuit. In semiconductor devices, diodes such as a Schottky barrier diode are often used as rectifying devices.
Schottky barrier diodes formed using a semiconductor substrate include, for example, a diode disclosed in Japanese Unexamined Patent Publication No. H05-55553, A Schottky barrier diode disclosed in Japanese Unexamined Patent Publication No. H05-55553 is configured such that an n+ region is formed in a portion of the surface layer of an n region, and an electrode is connected to each of the n+ region and the n region. In Japanese Unexamined Patent Publication No. H05-55553, the Schottky barrier diode is formed together with a bipolar transistor. The n region of the Schottky barrier diode is formed to have the same depth as that of a well.
In addition, Japanese Unexamined Patent Publication No. H09-55439 and Japanese Unexamined Patent Publication No. H10-28045 disclose semiconductor devices in which a MOS transistor and a Schottky barrier diode are formed together. Particularly, Japanese Unexamined Patent Publication No. H09-55439 discloses that a silicide is used as a Schottky electrode. In addition, Japanese Unexamined Patent Publication No. H10-28045 discloses that an n region is caused to be adjacent to an n+ region serving as a source or a drain of the MOS transistor, and that a Schottky electrode is connected to the n region.
In addition, Japanese Unexamined Patent Publication No. 2010-147387 and Japanese Unexamined Patent Publication No. 2011-243978 disclose that in compound semiconductor devices using two-dimensional electron gas, a Schottky electrode is provided in a region which is located between a gate electrode and drain in an electron supply layer, and that the Schottky electrode is electrically connected to a source.
Further, a non-patent document (S. Snakaran et al., J. Solid-State Circuit, 42, P. 1058, 2007) discloses that an element isolation film is located between two electrodes of a Schottky barrier diode.
Meanwhile, Japanese Unexamined Patent Publication No. 2005-175063 discloses that in a transistor including an n-type drift region, the transistor has a high withstanding voltage by providing a p-type impurity layer in the surface layer of a drift region.